20028640 has 48 divisors (see below), whose sum is σ = 47688480. Its totient is φ = 7948800.

The previous prime is 20028637. The next prime is 20028661. The reversal of 20028640 is 4682002.

20028640 = 73² + 74² + ... + 392².

It is a super-2 number, since 2×20028640² = 802292840499200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23746 + ... + 24574.

It is an arithmetic number, because the mean of its divisors is an integer number (993510).

Almost surely, 2^20028640 is an apocalyptic number.

20028640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20028640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23844240).

20028640 is an abundant number, since it is smaller than the sum of its proper divisors (27659840).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20028640 is a wasteful number, since it uses less digits than its factorization.

20028640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 995 (or 987 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 20028640 is about 4475.3368588297. The cubic root of 20028640 is about 271.5712680623.

The spelling of 20028640 in words is "twenty million, twenty-eight thousand, six hundred forty".